There are generally three or four weeks of severe cold, during which the thermometer sometimes at night sinks below zero, and sometimes in the day does not rise to the point of thaw. This period is generally enlivened by two or three snow storms, which set in motion the rapid sleighs, the jingle of whose lively bells is heard through day and night. The Delaware is not frozen over every winter, but there is always made an ample supply of fine crystalline ice to last the citizens until the next winter. The annual average duration of interrupted navigation may be four or five weeks. In March there is sometimes a little Scotch weather in which Sawney would rub his hands and tell you, here is a fine cauld blawey snawey rainy day. There is however not much such weather, though the March winds have been known to blow (as Paddy would say,) even in the first week of April; after which spring begins with tears and smiles to coax the tardy vegetation into life. Spring is short and vegetation rapid. Summer sprinkles a day here and there in May, and sets in seriously to toast people in June; during which month there are generally six or eight days whose average temperature reaches the altissimum of summer heat. In July the days are hot, but there is some relief at night; whilst in August the fiery day is but a prelude to a baking night; and the whole city has the air of an enormous oven.[4] The extremely hot weather does not continue more than six weeks, and so far from being a misfortune, it is a great advantage to the inhabitants; for it makes every body that can spare twenty dollars, take a pleasant journey every year, whereby their minds are expanded, their manners improved, and they return with a double zest to the enjoyments of Philadelphia, having learned, quantum est in rebus inane, that is, in the rebuses of other places. [Footnote 4: The season of the Dog Days. A witty Philadelphia lady being once asked, how many Dog Days there are, answered that there must be a great many, for every dog has his day. At that time the city abounded in dogs, but the corporation has since made fierce war upon them, with a view perhaps of lessening the number of Dog Days, and improving the climate, by _curtailing_ those innocent beasts.] The autumn, or as the Philadelphians call it, the Fall, is the most delightful part of the year, and is sometimes eked out by the Indian Summer as far as Christmas. The Fall begins in the first half of September and generally lasts until the middle of November, when it is succeeded by the Indian Summer; a pleasant period of two or three weeks, in which the mornings, evenings and nights are frosty, and the days comfortably warm and a little hazy. The Indians are supposed to have employed this period in hunting and laying in game for winter use, before the long-knives made game of _them_. The population of Philadelphia and its suburbs exceeds 180,000 souls.